Electronic mail (or "e-mail") message delivery systems as well as voice mail systems have gained significantly in popularity in recent years, enabling information to be efficiently and rapidly communicated to large numbers of people. Such systems allow groups of people to communicate without having to arrange a specific time to meet or talk on the telephone.
The sender of a voice or e-mail message can designate any number of addressees, and can request a reply from the addressees. In this way, for example, a proposal could be sent to a number of people for review and comment, with the reviewers replying directly to the sender of the message.